Snowmaking machines commonly fall into two basic categories: air systems which employ a combination of compressed air and water passing through a single nozzle, and so-called airless systems, which do not have a requirement of compressed air or use only relatively small amounts of compressed air to generate ice nuclei. Regardless of which system is used, certain problems are inherent in the manufacture of snow. Downstream of the discharge section of a snow-making machine, inevitably a wet spot will occur, which is caused by water droplets are not suspended in the air long enough to crystallize into snow. The second problem is that in some instances a portion of the snow-ice-plume discharged from a snowmaking machine will remain airborne and drift outside the desired area for deposition of snow.
I have determined after a careful analysis that the drop size distribution produced by the water nozzles used in the manufacture of snow is the most important contributing factor to these problems. Basically, in the plume discharged from a snow-making machine, there is a wide distribution in drop size. The large drops, because of their weight, tend to fall out of the wake stream subsequent to discharge and fall on the ground, causing the wet spots immediately downstream of the snow-making machine. The small drops remain airborne for a considerably longer period of time than is necessary to form snow and tend to fall to the ground far outside the desired area. This problem is particularly acute in those airless systems which employ the movement of large volumes of air to project the snow onto the area to be covered or in compressed air systems employing water only nozzles to add more water spray to the basic pneumatically atomized stream.
The water nozzles commercially used today in airless systems rated for a particular drop size in fact provide a wide distribution of drop sizes for any given fluid pressure and orifice size. This is generally true whether pressure, spinning disk, or pneumatic atomization is employed. Thus, even if an optimum drop size is desired for the operation of a particular snow-making machine, the use of commercially available nozzles will not solve the aforementioned problems because of the inherent wide variance in drop size.